[SPARK-7008][SDP][ML] Make org.apache.spark.sql.pipelines internal package and make EstimatorUtils private

### What changes were proposed in this pull request?
Make org.apache.spark.sql.pipelines internal package and make EstimatorUtils private

### Why are the changes needed?
they should not be exposed to end users

### Does this PR introduce _any_ user-facing change?
no

### How was this patch tested?
ci

### Was this patch authored or co-authored using generative AI tooling?
no

Closes #53444 from zhengruifeng/mk_EstimatorUtils_private.

Authored-by: Ruifeng Zheng <[email protected]>
Signed-off-by: Wenchen Fan <[email protected]>

Author: zhengruifeng

mllib/src/main/scala/org/apache/spark/ml/Estimator.scala

@@ -106,7 +106,7 @@ abstract class Estimator[M <: Model[M]] extends PipelineStage {
 }
 
 
-object EstimatorUtils {
+private[spark] object EstimatorUtils {
   // This warningMessagesBuffer is for collecting warning messages during `estimator.fit`
   // execution in Spark Connect server.
   private[spark] val warningMessagesBuffer = new java.lang.ThreadLocal[ArrayBuffer[String]]() {

project/SparkBuild.scala

@@ -367,6 +367,7 @@ object SparkBuild extends PomBuild {
         "org.apache.spark.kafka010",
         "org.apache.spark.network",
         "org.apache.spark.sql.avro",
+        "org.apache.spark.sql.pipelines",
         "org.apache.spark.sql.scripting",
         "org.apache.spark.types.variant",
         "org.apache.spark.ui.flamegraph",
@@ -1531,6 +1532,7 @@ object Unidoc {
       .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/classic/")))
       .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/execution")))
       .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/internal")))
+      .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/pipelines")))
       .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/scripting")))
       .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/ml")))
       .map(_.filterNot(_.getCanonicalPath.contains("org/apache/spark/sql/hive")))